SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dbf6c45ae5b459d98e3f141983c1f9327cd0043c536e41034f293008df58fd4c' 
  AND token = 'FxUnMhxp/S8Cu6jJHyTYSfRfsGCaCGZ3/CFvG+Ltkzg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}